Oxidative cross-linking of potato proteins by fungal laccases: Reaction kinetics and effects on the structural and functional properties

摘要

Aiming at developing biocatalytic approach to modulate potato proteins functionalities, laccase-catalyzed oxidative cross-linking of potato proteins was investigated in terms of enzyme kinetics, reaction time course and product structural-functional properties. The catalytic efficiency (kcat/Km, mM-1S-1) of fungal laccases in oxidizing patatin-enriched potato protein (PAT, 0.010-0.748) was higher than that of potato protease inhibitors (PIs, 0.008-0.184). While PIs formed more efficiently oxidative cross-linked products. Cross-linking of potato proteins were achieved by laccase alone or by laccase-ferulic acid system; ferulic acid contributed to higher crosslinking extent and to the antioxidant activity of modified proteins. Potato proteins exhibited similar or slightly enhanced solubility upon cross-linking, except that highly cross-linked PIs (cross-linking extent >30%) obtained from Coriolus hirsutus laccase (LacCh)-treatments showed reduced solubility. General improvement in the emulsification property of potato proteins was observed upon cross-linking. Cross-linked potato proteins from LacCh-6 h treatment showed good foaming property; these proteins exhibited enhanced molecular flexibility and the characteristics of mild cross-linking extent (9.6-17.1%) with the accumulation of moderate molecular weight fraction (PAT:60-80 kDa, PIs:30-40 kDa). This study will lay foundations for the exploitation of potato proteins as functional ingredients.